Three-dimensional microfluidic micro-droplet arrays for electronic integrated circuit and component cooling, energy-harvesting, chemical and biochemical microreactors, miniature bioreactors, and other applications

ABSTRACT

A microfluidic transport system for transporting microdroplets in three spatial dimensions. In an example arrangement, a first planar arrangement for transporting microdroplets in two spatial dimensions responsive to electric fields created by electrical operation of electrodes is fluidically connected by one or more conduits to other planar arrangement for transporting microdroplets in two spatial dimensions responsive to electric fields created by electrical operation of electrodes. Microdroplets can be transported through the one or more conduits so as to be moved among the first and second planar arrangements. 
     The system can be used for heat transfer, fluidic transfer, and other uses, and can be implemented within a printed circuit board, integrated circuit housing, or using materials such as metal, glass, polymer, plastic, layered materials, fibrous materials, etc. Example applications include integrated circuit cooling, energy harvesting, microfluidic systems, chemical reactors, biochemical reactors, chemical analysis arrangements, biochemical analysis arrangements, and other apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. Section 119(e), this application claims benefit ofpriority from Provisional U.S. Patent Application Ser. No. 61/599,643,filed Feb. 16, 2012, the contents of which are incorporated by referencein their entirety.

COPYRIGHT & TRADEMARK NOTICES

A portion of the disclosure of this patent document may containmaterial, which is subject to copyright protection. Certain marksreferenced herein may be common law or registered trademarks of theapplicant, the assignee or third parties affiliated or unaffiliated withthe applicant or the assignee. Use of these marks is for providing anenabling disclosure by way of example and shall not be construed toexclusively limit the scope of the disclosed subject matter to materialassociated with such marks.

BACKGROUND

1. Field

Aspects of the example implementations pertain to the areas ofthermoelectric devices and microfluidics, and more specifically tothree-dimensional microfluidic micro-droplet arrays for electronicintegrated circuit and component cooling, energy-harvesting, and otherapplications.

2. Overview

The cooling and energy harvesting of heat-producing integrated circuitsand other electronic components in computers, particularly in largehigh-density blade servers and data center environments, is a topic bothdeserving of and gaining considerable importance to commerce.Technologies addressing these problems and opportunities can be found,for example, in pending U.S. patent application Ser. No. 13/385,411 andthe references therein, including chapter 1 of the text Adaptive Coolingof Integrated Circuits Using Digital Microfludics by P. Paik, K.Chakrabarty, and V. Pamula, published by Artech House, Inc., Norwood,Me., Artech House, 2007, ISBN 978-1-59693-138-1.

The cooling of heat-producing integrated circuits in computers by meansof controlled electrowetting micro-droplet transport via microfluidicdevice structures has been considered in considerable detail in theabove-cited text by Paik, Chakrabarty, and Pamula. In Chapter 6 of thattext, those authors describe approaches to implementing microfluidicdevice structures for controlled electrowetting micro-droplet transportfor integrated circuit cooling using Printed Circuit Boards (“PCBs”).

In the afore-cited text, those authors describe first other approachesand general aspects of controlled electrowetting micro-droplet transportvia microfluidic device structures. For example, FIG. 1a , adapted fromthe afore-cited text, depicts a side view representation of amicrofluidic electrowetting micro-droplet transport “chip”implementation fitted over an integrated circuit package and in turn inthermal contact with an active cooling element such as a thermoelectriccooler. Additionally, FIG. 1b , adapted from the afore-cited text,depicts a top view representation of a number of micro-droplets beingtransported (via electrowetted transport) through various straight andright-angle-turn paths over a planar array of microelectrodes comprisedby such a microfluidic electrowetting micro-droplet “chip.” Themicro-droplets are transported over the planar array of microelectrodesin tightly-controlled fashion by temporally sequencing the electricpotential applied to individual microelectrodes. The micro-droplets aremoved into areas of thermal contact with portions of a heat-producingintegrated circuit dye, housing, packaging, heat-sink, etc., where theyabsorb heat and then are moved to other areas, volumes, or reservoirswhere the absorbed heat can be discharged, for example by means of anactive cooling element such as a thermoelectric cooler. In addition tothe transport of micro-droplets, those authors describe various means ofcontrolling the surface-area and temporal duration of micro-dropletsexposure to heat sources, droplet routing strategies, and otherinnovations. Also useful experimental data resulting from prototypes arereported, including the fact that larger droplets with longer exposuretimes to heat sources perform cooling functions better than smallerdroplets with shorter exposure times to heat sources.

In the afore-cited text, those authors later describe adapting themicrofluidic electrowetting micro-droplet planar microelectrode arrayand micro-droplet transport to implementations using Printed CircuitBoards (“PCBs”). Two approaches are considered in some detail, thesebeing the “confined system” represented in FIG. 2 and the “open system”represented in FIG. 3. In each of these systems, micro-droplets aremoved into areas of thermal contact with portions of a heat-producingintegrated circuit dye, housing, packaging, heat-sink, etc., where theyabsorb heat and then are moved (via sequencing the electric potentialapplied to the microelectrodes) to other areas, volumes, or reservoirswhere the absorbed heat can be discharged. FIGS. 4a and 4b (each adaptedfrom Adaptive Cooling of Integrated Circuits Using Digital Microfluidicsby P. Paik, K. Chakrabarty, and V. Pamula, Artech House, 2007, ISBN978-1-59693-138-1) depict example routing paths of micro-droplets overthe planar microelectrode array.

However, in the afore-cited text, those authors limit themselves toplanar microelectrode arrays and accordingly planar micro-droplettransport paths. For a micro-droplet exposed to heat in central areas ofa microelectrode array and which must then be transported to the edgesof the microelectrode array to dispense the absorbed heat, themicro-droplets can unfortunate radiate heat back into other portions ofthe heat-producing integrated circuits. Those authors allude to methodsfor minimizing the time over which unintended heat-radiation can occurby heated microdroplets.

Further, the afore-cited text does not provide consideration to avoidingundesired electromagnetic field and electrical field effects that caninterfere with adjacent high-performance electronic circuitry.

In addition to these issues and problems, the afore-cited text onlyconsiders the cooling of heat-producing integrated circuits. Energyharvesting is not considered.

Accordingly, the reciprocal properties of heat transfer and energyharvesting (via classical Peltier and Seebeck processes) are notconsidered, nor therefore arrangements to implement adaptive selectionbetween cooling and energy harvesting modalities.

Additionally, the afore-cited text only considers traditionalsemiconductor thermoelectric elements and does not cite nor anticipatethe far higher-efficiency quantum-based thermoelectric materials such asquantum well and Atvo metals. These transform classical Peltier andSeebeck processes to vastly different effects with not only radicallyimproved performance crossing (for the first time) importantapplication-feasibility thresholds but also, in many areas, entirelydifferent engineering and economic tradeoffs.

SUMMARY

Example implementations of example embodiments described herein addresseach of the aforementioned issues of the related art, by:

-   -   Implementation of 3D micro-droplet transit structures suitable        for thermal cooling and/or energy harvesting applications, and        further doing so in a manner suitable for implementation in        inexpensive multilayer Printed Circuit Boards (“PCBs”);    -   Incorporating electrical-field shielding in the above 3D        micro-droplet transit structures and PCB implementations to        avoid undesired electromagnetic field and electrical field        effects that can interfere with adjacent high-performance        electronic circuitry;    -   Using the above 3D micro-droplet transit structures and PCB        implementations to avoid undesired heat radiation by heated        micro-droplets as they are transported in areas with thermal        contact to the electronic component or other heat-producing        element;    -   Using the above 3D micro-droplet transit structures to        facilitate arrangements to implement adaptive selection between        cooling and energy harvesting modalities.    -   Employing higher-efficiency quantum-based thermoelectric        materials, such as quantum well and Atvo metals, so as to        radically improved performance beyond important        application-feasibility thresholds and access entirely different        engineering and economic tradeoffs.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and features will become more apparent uponconsideration of the following description of preferred embodimentstaken in conjunction with the accompanying drawing figures, wherein:

FIG. 1a (adapted from Adaptive Cooling of Integrated Circuits UsingDigital Microfluidics by P. Paik, K. Chakrabarty, and V. Pamula, ArtechHouse, 2007, ISBN 978-1-59693-138-1) depicts a side view representationof a microfluidic electrowetting micro-droplet transport “chip”implementation fitted over an integrated circuit package and in turn inthermal contact with an active cooling element such as a thermoelectriccooler.

FIG. 1b (adapted from Adaptive Cooling of Integrated Circuits UsingDigital Microfluidics by P. Paik, K. Chakrabarty, and V. Pamula, ArtechHouse, 2007, ISBN 978-1-59693-138-1) depicts a top view representationof a number of micro-droplets being transported (via electrowettedtransport) through various straight and right-angle-turn paths over aplanar array of microelectrodes comprised by such a microfluidicelectrowetting micro-droplet “chip.”

FIG. 2 (adapted from Adaptive Cooling of Integrated Circuits UsingDigital Microfluidics by P. Paik, K. Chakrabarty, and V. Pamula, ArtechHouse, 2007, ISBN 978-1-59693-138-1) depicts a “confined system”adaptation of the microfluidic electrowetting micro-droplet planarmicroelectrode array and micro-droplet transport to implementationsusing Printed Circuit Boards (“PCBs”).

FIG. 3 (adapted from Adaptive Cooling of Integrated Circuits UsingDigital Microfluidics by P. Paik, K. Chakrabarty, and V. Pamula, ArtechHouse, 2007, ISBN 978-1-59693-138-1) depicts an “open system” adaptationof the microfluidic electrowetting micro-droplet planar microelectrodearray and micro-droplet transport to implementations using PrintedCircuit Boards (“PCBs”).

FIGS. 4a and 4b (each adapted from Adaptive Cooling of IntegratedCircuits Using Digital Microfludics by P. Paik, K. Chakrabarty, and V.Pamula, Artech House, 2007, ISBN 978-1-59693-138-1) depict examplerouting paths of micro-droplets over the planar microelectrode array.

FIG. 5 depicts a representation of the “top” or “bottom” view of anexample array of microelectrodes, each microelectrode rendered as aconductor area on a Printed Circuit Board (PCB) and provided with anassociated electrically-conducting “trace” for electrically connectingthe microelectrode to voltage potential control circuitry, and,interspersed between some pairs of electrodes, a physical open holesuitable for a micro-droplet to travel through.

FIG. 6 depicts a side-view representation of an example two-layermicro-droplet transport arrangement with conduits linking the twomicro-droplet transport region.

FIG. 7 depicts the example arrangement depicted in FIG. 6 wherein theleftmost microelectrode on the lower micro-droplet transport region isprovided with a voltage potential with respect to the lower electricground plane that physically attracts a micro-droplet (depicted here asa black blob), causing it to move towards said leftmost microelectrode.

FIG. 8 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the leftmost microelectrodefor an interval of time. FIG. 8 can also depict a transient situation ofmicro-droplet transport wherein the momentum of the micro-droplet is notsuppressed (i.e., the micro-droplet is not locked into position underthe leftmost microelectrode for an interval of time).

FIG. 9 depicts the deactivation of the previously applied voltagepotential to the leftmost microelectrode and the application of thevoltage potential to the microelectrode immediately to the right in thedepiction, this causing the micro-droplet to be attracted toward themicroelectrode immediately to the right and move towards it.

FIG. 10 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 10 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

FIG. 11 depicts the deactivation of the previously applied voltagepotential to the leftmost microelectrode and the application of thevoltage potential to the microelectrode immediately to the right in thedepiction, this causing the micro-droplet to be attracted toward themicroelectrode immediately to the right and move towards it.

FIG. 12 depicts the situation where wherein the momentum of themicro-droplet is not suppressed (i.e., the micro-droplet is not lockedinto position under the activated microelectrode for an interval oftime) and the micro-droplet continues moving a bit beyond the immediateregion crowned by the activated microelectrode.

FIG. 13 also depicts a situation where wherein the momentum of themicro-droplet is not suppressed (i.e., the micro-droplet is not lockedinto position under the activated microelectrode for an interval oftime) and the micro-droplet continues moving a bit beyond the immediateregion crowned by the activated micro electrode.

FIG. 14 depicts the deactivation of the previously applied voltagepotential to the activated microelectrode of FIG. 13 and the applicationof the voltage potential to the microelectrode immediately to the right,this causing the micro-droplet to be attracted toward the microelectrodeimmediately to the right and move towards it.

FIG. 15 depicts a situation where wherein the momentum of themicro-droplet is not suppressed (i.e., the micro-droplet is not lockedinto position under the activated microelectrode for an interval oftime) and the micro-droplet continues moving a bit beyond the immediateregion crowned by the activated microelectrode. Here the micro-dropletmoves towards the opening of the conduit joining the lower micro-droplettransport region and the upper micro-droplet transport region.

FIG. 16 depicts a situation where the micro-droplet continues itsmovement to the right within the lower micro-droplet transport region,bypassing the chance to travel through the conduit joining the lowermicro-droplet transport region and the upper micro-droplet transportregion.

FIG. 17 depicts an example alternative to the course represented by FIG.16, herein where the momentum of the micro-droplet is suppressed by thesimultaneous activation of the microelectrodes on either side of theconduit joining the lower micro-droplet transport region and the uppermicro-droplet transport region and maintaining this condition for anadequate length of time for the micro-droplet to recover from thedepicted motion and (via surface tension or other droplet-maintainingprocesses and forces) settle into a stable position under the depictedactivated electrode.

FIGS. 18a-18b, 19a-19b, 20a-20d, 21a-21b, 22a-22b, 23a -23 c, 24 a-24 b,and 25 a-25 c depict two alternative arrangements for transmissionthrough a first conduit joining two droplet-transport layers from anon-heat-gathering-layer to a heat-gathering-layer and transmissionthrough a second conduit joining the two droplet-transport regions so asto return to a non-heat-gathering-layer. Specifically, the sequencedepicted in the series of FIGS. 18a, 19a, 20a, 21a, 22a, 23a, 24a, and25a depict transmission employing capillary forces and electric fieldsfrom distant microelectrodes, while comparatively the sequence depictedin the series of FIGS. 18b, 19b, 20b, 20c, 20d, 21b, 22b, 23b, 23c, 24b,25b , and 25 c depict controlled transmission employing proximatemicroelectrodes.

FIG. 26 depicts the attraction of the micro-droplet to a regionimmediately to the right of the second conduit joining the twodroplet-transport regions via activation of the microelectrodeimmediately to the right of the second conduit joining the twodroplet-transport regions.

FIG. 27 depicts the attraction of the micro-droplet towards the nextmicroelectrode by activation of that microelectrode.

FIG. 28 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 28 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

FIG. 29 depicts the attraction of the micro-droplet towards the nextmicroelectrode by activation of that microelectrode.

FIG. 30 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 30 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

FIG. 31 depicts the attraction of the micro-droplet towards the nextmicroelectrode by activation of that microelectrode.

FIG. 32 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 30 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

FIG. 33 depicts a general thermodynamics passive heat transfer processfrom a hot body to a broader environment.

FIG. 34a depicts a heat pump arrangement for an active heat transferprocess from a hot body to a broader environment. Energy is applied overtime to the heat pump (amounting to applied work) and consumed in theheat-pumping process.

FIG. 34b depicts a heat engine arrangement for an active heat transferprocess from a hot body to a broader environment. Energy is harvestedover time by the heat engine (amounting to harvested work) and consumed(at least in part) by external processes.

FIG. 35a depicts a representation of heat transfer from the previouslyheated micro-droplet to the electrical ground plane.

FIG. 35b depicts a representation of heat transfer from the previouslyheated micro-droplet to the electrical ground plane and further into thematerial joined to the electrical ground plane.

FIG. 35c depicts a representation of heat transfer from the previouslyheated micro-droplet to the electrical ground plane and further into alocal thermal conducting structure joined to the electrical groundplane.

Each of the situations depicted in FIGS. 35a-35c are special cases ofthe abstract representation depicted in FIG. 33.

FIG. 36 depicts a variation on the arrangement of FIG. 35b wherein thematerial joined to the electrical ground plane comprises a “global”(large area) thermoelectric structure.

FIG. 37 depicts a variation on the arrangements of FIG. 35c and FIG. 36combining features from each, wherein heat is transferred from thepreviously heated micro-droplet to a local (small area) thermoelectricstructure.

FIG. 38 depicts a variation on the arrangement of FIG. 35b comprising aplurality of local (small area) thermoelectric structures. In anembodiment, each local thermoelectric structure can separately attend toprocessing heat from properly positioned previously heatedmicro-droplet.

FIG. 39 depicts an expanding variation on the arrangement of FIG. 38wherein the electrical ground plane depicted throughout earlier figuresis replaced by an extended array of local thermoelectric structures.

FIG. 40a depicts three planar arrangements for transportingmicrodroplets of fluidic material in two spatial dimensions(heavier-lined) arranged with openings for interlinking conduits and aconnecting section (lighter-lined) providing conduit pathways betweenthese two layers.

FIG. 40b depicts a final assembly of the three example planarmicrodroplet transport arrangement layers assembled together interleavedwith the two example connecting sections presented in FIG. 40 a.

FIG. 40c depicts a representation of an example comprising some numberof planar microdroplet transport arrangement layers, said number greaterthan three.

FIG. 41a depicts an example arrangement wherein pairs of planarmicrodroplet transport arrangement layers are connected strictlypairwise.

FIG. 41b depicts an example wherein at least one common extended conduitis used to connect three microdroplet transport arrangement layers.

FIG. 41c depicts an example arrangement wherein the arrangements ofFIGS. 41a and 41b are combined.

FIG. 42a depicts an arrangement that implements a connectivemicrodroplet transport topology of at least a linear three-dimension(‘tube’) lattice.

FIG. 42b depicts a linear three-dimension (‘tube’) microdroplettransport lattice that can be implemented by the arrangement in FIG. 42ab.

FIG. 42c illustrates a group of pairwise conduits that interconnect themicrodroplet transport lattices within the three depicted microdroplettransport arrangement layers in a ring topology.

FIG. 43 depicts an example use of a single microdroplet transportarrangement layer configured to serve as a microfluidic bus in serviceto four other microdroplet transport arrangement layers.

FIG. 44a depicts an example representation wherein a layer in athree-dimensional microdroplet arrangement can internally fluidicallyinterface to one or more chemical and/or biochemical reactor elements,one or more chemical and/or biochemical analysis arrangements, one ormore cell culture chambers, one or more chemical and/or biochemicalsensors, one or more controlled valves, and/or other apparatus withinthat layer

FIG. 44b depicts a representation of an example comprising at leastseveral such layers.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawing figures which form a part hereof, and which show by way ofillustration specific implementations of example embodiments describedherein. It is to be understood by those of ordinary skill in thistechnological field that other embodiments may be utilized, andstructural, electrical, as well as procedural changes may be madewithout departing from the scope of the inventive concept.

In the following description, numerous specific details are set forth toprovide a thorough description of various embodiments. Certainembodiments may be practiced without these specific details or with somevariations in detail. In some instances, certain features are describedin less detail so as not to obscure other aspects. The level of detailassociated with each of the elements or features should not be construedto qualify the novelty or importance of one feature over the others.

Example Basic Configurations

Various embodiments can be implemented in a number of widely variedways. This opening section provides a few example basic configurationsas an orienting starting point. Many variations on this are providedexample basic configuration throughout other sections of the document.None of the example configurations are to be regarded as limiting.

Initial embodiments, example arrangements, and various exampleimplementations are first described in terms of a heat transferapplication, providing considerable detail relevant to both thatapplication area as well as several other applications. These teachingsare then extended to other applications by provided descriptions ofvariations, adaptations, and/or substitutions.

Example Basic Configurations Applicable to Heat-Transfer Applications

FIG. 5 depicts a representation of the “top” or “bottom” view an examplearray of microelectrodes, each microelectrode rendered as conductor areaon a Printed Circuit Board (PCB) and provided with an associatedelectrically-conducting “trace” for electrically connecting themicroelectrode to voltage potential control circuitry, and interspersedbetween some pairs of electrodes a physical open hole suitable for amicro-droplet to travel through. (Most of the subsequent remainingFigures show a side-view representation incorporating a side-view of thearrangement in FIG. 5.)

FIG. 6 depicts a side-view representation of an example two-layermicro-droplet transport arrangement with conduits linking the twomicro-droplet transport region. This Figure incorporates a side-view ofthe arrangement like that depicted in FIG. 5. The view shown in FIG. 5would herein lie in the center facing downwards and comprises additionalmicroelectrodes; two of the physical open holes suitable for amicro-droplet to travel through depicted in FIG. 5 appear (in side-view)in FIG. 6 as the conduits linking the two micro-droplet transportregion. In the depiction of FIG. 6, above the upper micro-droplettransport region is a solid layer of PCB material punctuated withthermally-conducting segments that conduct heat from the item to becooled into the upper micro-droplet transport region. In this exampleembodiment, the punctuating thermally-conducting segments are alsoelectrical conductors configured to serve as an electrical ground planethat provides both electrical shielding and serves as the ground planefor forming electric fields for micro-droplet transport viaelectrowetting. Also in the depiction of FIG. 6, below the lowermicro-droplet transport region is a solid layer of material (forexample, PCB material) whose upper area comprises an electricalconductor layer configured to serve as an electrical ground plane thatprovides both electrical shielding and serves as the ground plane forforming electric fields for micro-droplet transport via electrowetting.

Example Micro-Droplet Transport Through Non-Heated Transport Region

FIG. 7 depicts the example arrangement depicted in FIG. 6 wherein theleftmost microelectrode on the lower micro-droplet transport region isprovided with a voltage potential with respect to the lower electricground plane that physically attracts a micro-droplet (depicted here asa black blob), causing it to move towards said leftmost microelectrode.The motion of the micro-droplet towards that microelectrode provides themicro-droplet with momentum. In some embodiments the momentum can beutilized in the controlled transport of the micro-droplet towards thenext electrode to the right. In other embodiments the momentum can besuppressed by locking the micro-droplet into position under saidmicroelectrode for an interval of time, for example as depicted in FIG.8.

FIG. 8 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the leftmost microelectrodefor an interval of time. FIG. 8 can also depict a transient situation ofmicro-droplet transport wherein the momentum of the micro-droplet is notsuppressed (i.e., the micro-droplet is not locked into position underthe leftmost microelectrode for an interval of time).

FIG. 9 depicts the deactivation of the previously applied voltagepotential to the leftmost microelectrode and the application of thevoltage potential to the microelectrode immediately to the right in thedepiction, this causing the micro-droplet to be attracted toward themicroelectrode immediately to the right and move towards it. In someembodiments, the situation depicted in FIG. 9 occurs immediately afterthe situation depicted in FIG. 8. In other embodiments, the situationdepicted in FIG. 9 occurs immediately after the situation depicted inFIG. 7. Other strategies for sequencing the voltage potentials appliedto the microelectrodes involved are also possible and provided for invarious implementations.

FIG. 10 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 10 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

FIG. 11 depicts the deactivation of the previously applied voltagepotential to the leftmost microelectrode and the application of thevoltage potential to the microelectrode immediately to the right in thedepiction, this causing the micro-droplet to be attracted toward themicroelectrode immediately to the right and move towards it. In someembodiments, the situation depicted in FIG. 11 occurs immediately afterthe situation depicted in FIG. 10. In other embodiments, the situationdepicted in FIG. 11 occurs immediately after the situation depicted inFIG. 9. Other strategies for sequencing the voltage potentials appliedto the microelectrodes involved are also possible and provided for invarious implementations.

FIG. 12 depicts the situation where wherein the momentum of themicro-droplet is not suppressed (i.e., the micro-droplet is not lockedinto position under the activated microelectrode for an interval oftime) and the micro-droplet continues moving a bit beyond the immediateregion crowned by the activated microelectrode. Alternatively, themicro-droplet can be locked into place by maintaining activation of theactivated electrode for an adequate length of time for the micro-dropletto recover from the depicted motion and (via surface tension or otherdroplet-maintaining processes and forces) settle into a stable positionunder the depicted activated electrode.

FIG. 13 also depicts a situation where wherein the momentum of themicro-droplet is not suppressed (i.e., the micro-droplet is not lockedinto position under the activated microelectrode for an interval oftime) and the micro-droplet continues moving a bit beyond the immediateregion crowned by the activated micro electrode. Alternatively, themicro-droplet can be locked into place by maintaining activation of theactivated electrode for an adequate length of time for the micro-dropletto recover from the depicted motion and (via surface tension or otherdroplet-maintaining processes and forces) settle into a stable positionunder the depicted activated electrode.

FIG. 14 depicts the deactivation of the previously applied voltagepotential to the activated microelectrode of FIG. 13 and the applicationof the voltage potential to the microelectrode immediately to the right,this causing the micro-droplet to be attracted toward the microelectrodeimmediately to the right and move towards it.

FIG. 15 depicts a situation where wherein the momentum of themicro-droplet is not suppressed (i.e., the micro-droplet is not lockedinto position under the activated microelectrode for an interval oftime) and the micro-droplet continues moving a bit beyond the immediateregion crowned by the activated microelectrode. Here the micro-dropletmoves towards the opening of the conduit joining the lower micro-droplettransport region and the upper micro-droplet transport region.

FIG. 16 depicts a situation where the micro-droplet continues itsmovement to the right within the lower micro-droplet transport region,bypassing the chance to travel through the conduit joining the lowermicro-droplet transport region and the upper micro-droplet transportregion.

Example Micro-Droplet Transport Through Conduits into and from HeatedTransport Region

FIG. 17 depicts an example alternative to the course represented by FIG.16, herein where the momentum of the micro-droplet is suppressed by thesimultaneous activation of the microelectrodes on either side of theconduit joining the lower micro-droplet transport region and the uppermicro-droplet transport region and maintaining this condition for anadequate length of time for the micro-droplet to recover from thedepicted motion and (via surface tension or other droplet-maintainingprocesses and forces) settle into a stable position under the depictedactivated electrode.

FIGS. 18a-18b, 19a-19b, 20a-20d, 21a-21b, 22a-22b, 23a -23 c, 24 a-24 b,and 25 a-25 c depict two alternative arrangements for transmissionthrough a first conduit joining two droplet-transport layers from anon-heat-gathering-layer to a heat-gathering-layer and transmissionthrough a second conduit joining the two droplet-transport regions so asto return to a non-heat-gathering-layer. As a first example, thesequence depicted in the series of FIGS. 18a, 19a, 20a, 21a, 22a, 23a,24a, and 25a depict example transmission employing a component ofcapillary forces and electric fields from distant microelectrodes. Otherapproaches differing in various ways from that depicted in this seriesof figures can also be used and are anticipated in the exampleembodiments.

Alternatively, microelectrodes can be provided in the conduits tofacilitate precise electrowetted transport, while comparatively thesequence depicted in the series of FIGS. 18b, 19b, 20b, 20c, 20d, 21b,22b, 23b, 23c, 24b, 25b , and 25 c depict example transmission throughthe first and second microelectrode-including conduits joining the twodroplet-transport layers, wherein the transmission through the conduitsemploys essentially only proximate microelectrodes. The microelectrodescan be implemented within the conduits through a variety of ways,including insertion of prefabricated cylindrical structures within theconduits. Further, the voltage potential applied to microelectrodeswithin the conduit in various implementations and transport schemes takeon different values over time, for example sometime the electrowettedtransport voltage potential and sometimes the ground plane voltagepotential. In some implementations and transport schemes, other voltagepotentials can also or alternatively be used so as to manipulate thepath and shape of the micro-droplet as advantageous. Other approachesdiffering in various ways from that depicted in this series of figurescan also be used and are anticipated in the example embodiments.

While in the upper transport region (FIGS. 21a-b, 22a-22b, 23a-23c ) themicro-droplet absorbs heat generated by the item to be cooled throughthe thermal conducting layer segment and electrical ground plane, or viaother arrangements in alternate implementations. The absorbed heat inthe resulting heated micro-droplets can then be transported to otherregions where the heat can be processed in various ways (as in theexamples to be described as well as other ways applicable to variousapplications and/or alternate embodiments).

Example Continued Micro-Droplet Transport Through Non-Heated TransportRegion

FIG. 26 depicts the attraction of the micro-droplet to a regionimmediately to the right of the second conduit joining the twodroplet-transport regions via activation of the microelectrodeimmediately to the right of the second conduit joining the twodroplet-transport regions. The situation depicted in FIG. 26 can occurimmediately after the situation depicted in FIG. 16, or immediatelyafter the situation depicted in FIG. 25a , or immediately after thesituation depicted in FIG. 25c . Other strategies for sequencing thevoltage potentials applied to the microelectrodes involved are alsopossible and provided for in various implementations.

FIG. 27 depicts the attraction of the micro-droplet towards the nextmicroelectrode by activation of that microelectrode.

FIG. 28 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 28 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

FIG. 29 depicts the attraction of the micro-droplet towards the nextmicroelectrode by activation of that microelectrode.

FIG. 30 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 30 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

FIG. 31 depicts the attraction of the micro-droplet towards the nextmicroelectrode by activation of that microelectrode.

FIG. 32 can depict an arrangement for the suppression of micro-dropletmomentum by locking it into position under the activated microelectrodefor an interval of time. FIG. 30 can also depict a transient situationof micro-droplet transport wherein the momentum of the micro-droplet isnot suppressed (i.e., the micro-droplet is not locked into positionunder the activated microelectrode for an interval of time).

Thermodynamic Models Abstracting Various Types of Thermal Transfer fromHeated Micro-Droplets

FIG. 33 depicts a general thermodynamics passive heat transfer processfrom a hot body to a broader environment.

FIG. 34a depicts a heat pump arrangement for an active heat transferprocess from a hot body to a broader environment. Energy is applied overtime to the heat pump (amounting to applied work) and consumed in theheat-pumping process. Thermoelectric cooling (for example employing thePeltier process and analogous processes employing Avto metals andquantum well materials) is an example of such a heat pump arrangement.Additional considerations relating to the energy and work applied to theheat pump (for example Thomson effect, Joule heating, etc.) are notbrought forth in this representation.

FIG. 34b depicts a heat engine arrangement for an active heat transferprocess from a hot body to a broader environment. Energy is harvestedover time by the heat engine (amounting to harvested work) and consumed(at least in part) by external processes. Thermoelectric electriccurrent generation (for example employing the Seebeck process andanalogous processes employing Avto metals and quantum well materials) isan example of such a heat engine arrangement. Additional considerationsrelating to the energy and work applied to the heat engine (for exampleBenedicks effect, Joule heating, etc.) are not brought forth in thisrepresentation.

Example Micro-Droplet Thermal Transfer within Non-Heated TransportRegion

FIG. 35a depicts a representation of heat transfer from the previouslyheated micro-droplet to the electrical ground plane.

FIG. 35b depicts a representation of heat transfer from the previouslyheated micro-droplet to the electrical ground plane and further into thematerial joined to the electrical ground plane.

FIG. 35c depicts a representation of heat transfer from the previouslyheated micro-droplet to the electrical ground plane and further into alocal thermal conducting structure joined to the electrical groundplane.

Each of the situations depicted in FIGS. 35a-35c are special cases ofthe abstract representation depicted in FIG. 33.

Example Micro-Droplet Thermal Transfer To Thermoelectric Devices in theNon-Heated Transport Region and Resultant Capabilities

FIG. 36 depicts a variation on the arrangement of FIG. 35b wherein thematerial joined to the electrical ground plane comprises a “global”(large area) thermoelectric structure. In various embodiments thethermoelectric structure can be a thermoelectric cooler (an “electrical”case of the abstract heat pump representation depicted in FIG. 34a ), athermoelectric electric current generator (an “electrical” case of theabstract heat engine representation depicted in FIG. 34b ), or areciprocal thermoelectric device capable of operating in either athermoelectric cooler (i.e., an “electrical” heat pump) or athermoelectric electric current generator (i.e., an “electrical” heatengine) as determined by imposed thermal conditions and electricalconnections to the reciprocal thermoelectric device. In an embodiment,the role of electrical ground plane (used for micro-droplet transport)can be served by the electrical conditions and physical location of aportion of the thermoelectric device itself (such as electricallyconducting material joining two legs of the thermoelectric device). Insome embodiments, the role of electrical shielding (from electricalfield and electromagnetic generation noise) can also be served by theelectrical conditions and physical location of the same portion of thethermoelectric device itself. In other embodiments, the role ofelectrical shielding can also be served by the electrical conditions andphysical location of another portion of the thermoelectric deviceitself. In yet other embodiments, the role of electrical shielding canalso be served by another electrical shielding element.

FIG. 37 depicts a variation on the arrangements of FIG. 35c and FIG. 36combining features from each, wherein heat is transferred from thepreviously heated micro-droplet to a local (small area) thermoelectricstructure. In various embodiments the thermoelectric structure can be athermoelectric cooler, a thermoelectric electric current generator, or areciprocal thermoelectric device capable of operating in either athermoelectric cooler or a thermoelectric electric current generator asdetermined by imposed thermal conditions and electrical connections tothe reciprocal thermoelectric device. In an embodiment, the role ofelectrical ground plane (used for micro-droplet transport) can be servedby the electrical conditions and physical location of a portion of thethermoelectric device itself (such as electrically conducting materialjoining two legs of the thermoelectric device). In some embodiments, therole of electrical shielding (from electrical field and electromagneticgeneration noise) can also be served by the electrical conditions andphysical location of the same portion of the thermoelectric deviceitself. In other embodiments, the role of electrical shielding can alsobe served by the electrical conditions and physical location of anotherportion of the thermoelectric device itself. In yet other embodiments,the role of electrical shielding can also be served by anotherelectrical shielding element.

Additionally, in some embodiments, the thermoelectric device can serveas a temperature sensor.

In some embodiments, the mode of the thermoelectric device is switchedover time. As one example, the thermoelectric device can be athermoelectric cooler one moment and a temperature sensor at anothermoment. As another example, the thermoelectric device can be athermoelectric electric current generator one moment and a temperaturesensor at another moment. As yet another example, the thermoelectricdevice can be a thermoelectric cooler one moment and a thermoelectricelectric current generator at another moment. As still another example,the thermoelectric device can be a thermoelectric cooler one moment, atemperature sensor at another moment, and a thermoelectric electriccurrent generator at yet another moment.

FIG. 38 depicts a variation on the arrangement of FIG. 35b comprising aplurality of local (small area) thermoelectric structures. In anembodiment, each local thermoelectric structure can separately attend toprocessing heat from properly positioned previously heatedmicro-droplet. In an embodiment, the role of electrical ground plane canbe served by the electrical conditions and physical location of aportion of the thermoelectric device itself (such as electricallyconducting material joining two legs of the thermoelectric device), andthe individual portion of each of the plurality of thermoelectricdevices collectively serve as an electrical equivalent to an electricalground plane used for micro-droplet transport. In some embodiments, therole of electrical shielding (from electrical field and electromagneticgeneration noise) can also be served by the electrical conditions andphysical location of the same portion of the thermoelectric deviceitself. In other embodiments, the role of electrical shielding can alsobe served by the electrical conditions and physical location of anotherportion of the thermoelectric device itself. In yet other embodiments,the role of electrical shielding can also be served by anotherelectrical shielding element. In various embodiments, each of the localthermoelectric structures can be a thermoelectric cooler, athermoelectric electric current generator, or a reciprocalthermoelectric device capable of operating in either a thermoelectriccooler or a thermoelectric electric current generator as determined byimposed thermal conditions and electrical connections to the reciprocalthermoelectric device.

In some embodiments, all of the local thermoelectric structures arethermoelectric coolers. In other embodiments, all of the localthermoelectric structures are thermoelectric electric currentgenerators.

In yet other embodiments, each of the local thermoelectric structuresare reciprocal thermoelectric devices capable of operating in either athermoelectric cooler or a thermoelectric electric current generator asdetermined by imposed thermal conditions and electrical connections tothe reciprocal thermoelectric device. In some implementations of such(i.e., all reciprocal thermoelectric device) embodiments, all localthermoelectric structures are used in the same mode at the same time. Inother implementations of such (i.e., all reciprocal thermoelectricdevice) embodiments, a first plurality of local thermoelectricstructures are used in thermoelectric cooler mode at the same time thata second non-overlapping plurality of local thermoelectric structuresare used in thermoelectric electric current generator mode. In yet otherimplementations of such (i.e., all reciprocal thermoelectric device)embodiments, each of the local thermoelectric structures are reciprocalthermoelectric devices is configured to be independently operable ineither a thermoelectric cooler or a thermoelectric electric currentgenerator as determined by imposed thermal conditions and electricalconnections to the reciprocal thermoelectric device.

Additionally, in some embodiments, at least one of the thermoelectricdevices can serve as a temperature sensor.

In some embodiments, the mode of a given thermoelectric device isswitched over time. As one example, a given thermoelectric device can bea thermoelectric cooler one moment and a temperature sensor at anothermoment. As another example, a given thermoelectric device can be athermoelectric electric current generator one moment and a temperaturesensor at another moment. As yet another example, a given thermoelectricdevice can be a thermoelectric cooler one moment and a thermoelectricelectric current generator at another moment. As still another example,a given thermoelectric device can be a thermoelectric cooler one moment,a temperature sensor at another moment, and a thermoelectric electriccurrent generator at yet another moment.

FIG. 39 depicts an expanding variation on the arrangement of FIG. 38wherein the electrical ground plane depicted throughout earlier figuresis replaced by an extended array of local thermoelectric structures. Inan embodiment, the role of electrical ground plane can be served by theelectrical conditions and physical location of a portion of thethermoelectric device itself (such as electrically conducting materialjoining two legs of the thermoelectric device), and the individualportion of each of the plurality of thermoelectric devices collectivelyserve as an electrical equivalent to an electrical ground plane used formicro-droplet transport. In some embodiments, the role of electricalshielding (from electrical field and electromagnetic generation noise)can also be served by the electrical conditions and physical location ofthe same portion of the thermoelectric device itself. In otherembodiments, the role of electrical shielding can also be served by theelectrical conditions and physical location of another portion of thethermoelectric device itself. In yet other embodiments, the role ofelectrical shielding can also be served by another electrical shieldingelement. In various embodiments, each of the local thermoelectricstructures can be a thermoelectric cooler, a thermoelectric electriccurrent generator, or a reciprocal thermoelectric device capable ofoperating in either a thermoelectric cooler or a thermoelectric electriccurrent generator as determined by imposed thermal conditions andelectrical connections to the reciprocal thermoelectric device.

In some embodiments, all of the local thermoelectric structures arethermoelectric coolers. In other embodiments, all of the localthermoelectric structures are thermoelectric electric currentgenerators.

In yet other embodiments, each of the local thermoelectric structuresare reciprocal thermoelectric devices capable of operating in either athermoelectric cooler or a thermoelectric electric current generator asdetermined by imposed thermal conditions and electrical connections tothe reciprocal thermoelectric device. In some implementations of such(i.e., all reciprocal thermoelectric device) embodiments, all localthermoelectric structures are used in the same mode at the same time. Inother implementations of such (i.e., all reciprocal thermoelectricdevice) embodiments, a first plurality of local thermoelectricstructures are used in thermoelectric cooler mode at the same time thata second non-overlapping plurality of local thermoelectric structuresare used in thermoelectric electric current generator mode. In yet otherimplementations of such (i.e., all reciprocal thermoelectric device)embodiments, each of the local thermoelectric structures are reciprocalthermoelectric devices is configured to be independently operable ineither a thermoelectric cooler or a thermoelectric electric currentgenerator as determined by imposed thermal conditions and electricalconnections to the reciprocal thermoelectric device.

Additionally, in some embodiments, at least one of the thermoelectricdevices can serve as a temperature sensor.

In some embodiments, the mode of a given thermoelectric device isswitched over time. As one example, a given thermoelectric device can bea thermoelectric cooler one moment and a temperature sensor at anothermoment. As another example, a given thermoelectric device can be athermoelectric electric current generator one moment and a temperaturesensor at another moment. As yet another example, a given thermoelectricdevice can be a thermoelectric cooler one moment and a thermoelectricelectric current generator at another moment. As still another example,a given thermoelectric device can be a thermoelectric cooler one moment,a temperature sensor at another moment, and a thermoelectric electriccurrent generator at yet another moment.

Arrangements such as those depicted in FIG. 39 (and to some extent FIG.38) provide a wide range of capabilities. As one example, localthermoelectric elements on the left side of the figure could remove heatfrom previously-heated micro-droplets and then send the cooledmicro-droplets to the upper level for another cycle of heat gathering.As another example, the duration of a micro-droplets exposure to heat inthe upper region can be modulated by the measured temperature ofprevious heated micro-droplets returning from that particular area ofthe item to be cooled. As yet another example, local thermoelectricelements on the left side of the figure could pre-cool micro-droplets tobelow-ambient temperatures and then send the extra-cool micro-dropletsto the upper level for a cycle of additional heat gathering. Many othercapabilities are made possible by various embodiments, implementations,and adaptations.

Thermal Fluids (“Thermofluids”) and Their Conditioning for DropletTransport in Cooling Applications

Thermal fluids (also known as “thermofluids”) suitable for heattransport with various performance and physical properties are known,for example propylene glycol, ethylene glycol, various types of oilsincluding various types of liquid polymerized siloxane (“silicone oil”),and specialty thermal fluids, for example such as those sold byDuratherm, P.O. Box 563, Lewiston, N.Y., 14092 and Dow Chemical Company,P.O. Box 1206, Midland, Mich. U.S.A. 48674. Thermal fluids can beconditioned in various fashions to behave more suitably for microdropletformation and integrity, for example by employing one or more surfactantmaterials. It is to be expected that the viscosity and interfacialtension (factors in droplet stability, formation, and mechanics) of athermal fluid will vary at least somewhat with temperature, and inchoice of both the thermal fluid and any treatment components (such assurfactants) the range of anticipated temperature extremes that can beexpected must be considered to avoid unwanted material breakdowns, phasechanges, decompositions, etc.

Electrode Sequencing and Related Droplet Transport Issues

The sequencing of electrode-driven electrical manipulation of dropletsis known. Discussion of design issues for droplet transport can befound, for example, in pp. 56-60 of Adaptive Cooling of IntegratedCircuits Using Digital Microfludics by P. Paik, K. Chakrabarty, and V.Pamula, published by Artech House, Inc., Norwood, Me., Artech House,2007, ISBN 978-1-59693-138-1.

For cooling applications, it is to be expected that a number ofdroplets, and perhaps a relatively large number, will be in transportsimultaneously. In some implementations or situations it can beadvantageous to route droplets continuously according to a predefinedpattern that is executed in a periodic fashion. The rate at which thepattern is executed can in some implementations or situations beadvantageously varied in time in response to temperature or competingtasks.

In other situations, more complex routing of more arbitrary types ofroutes, each with associated requirements, can be expected. In somecases, various droplet transport tasks can compete for shared transportpaths. Methods for droplet planning and scheduling accordingly canbecome more complex and in many situations can be optimally designed.Some representative techniques applicable to these situations are taughtby K. Bohringer, “Modeling and Controlling Parallel Tasks inDroplet-based Microfluidic Systems,” in Design Automation Methods andTools for Microfluidics-Based Biochips, K. Chakabarty, J. Zeng (ed.),Springer, ISBN 1-4020-5122-0, 2006, pp. 301-327

Use of Surface Acoustic Wave Transport instead of Electrode ArrayTransport

As an alternative or supplement to electrode-driven electricalmanipulation of droplets, various embodiments and implementations canadvantageously incorporate the use of Surface Acoustic Wave (SAW)droplet transport is known, for example as taught in P. Tabourier, J.-C.Camart, C. Druon, “Surface acoustic wave two-dimensional transport andlocation of microdroplets using echo signal,” Journal of AppliedPhysics, Volume: 100, Issue 11, pp. 116101-116101-3.

Use for Heating, Heating/Cooling, Temperature Equilibrium

As an alternative or supplement to cooling, various embodiments andimplementations can advantageously incorporate the aforementioned heattransfer mechanisms in reverse so as to deliver heat from the outsideworld or other source to one or more target elements, for example todeliver heat to a reaction element or cell culture chamber. Accordingly,the aforementioned heat transfer mechanisms can thus also be used forcombined heating and cooling for robust temperature control, exchangingheat between entities to attain thermal equilibrium, etc.

Incorporation of Sensors

Various embodiments and implementations can advantageously incorporatevarious types of sensors responsive to or interrogating microdroplets,for example temperature sensors, capacitive sensors, optical sensors,bioFET sensors, acoustic wave sensors, electric-field sensors, etc. Insome embodiments and implementations the signals provided from suchsensors can advantageously used for reporting measurements, feedbackcontrol for droplet transport rate modulation, feedback control fordroplet transport routing, feedback control for droplet transport taskscheduling, feedback control for higher-level task scheduling, and otherapplications.

Incorporation of Controlled Valves

As an alternative or supplement to electrode-driven electricalmanipulation of droplets, various embodiments and implementations canadvantageously incorporate the use of microfluidic or other types ofcontrolled valves to direct microdropets, provide controlled access toreservoirs, seal and provide access to reaction chambers, interface withdroplet-creation nozzles, as well as other uses.

Closed-Loop Fluidic Routing

Various embodiments and implementations can advantageously incorporateclosed-system routing of microdroplets. For example, in a coolingapplication, microdroplets of thermal fluid can circulate in a coolingarrangement, delivering heat to or from a thermoelectric device.

External-System Fluidic Interfaces

Various embodiments and implementations can advantageously incorporatefluidic interfaces to external systems, external reservoirs,droplet-creation nozzles, etc.

Various embodiments and implementations can advantageously incorporatecontrolled valves in the input and/or output structure for externalsystem fluidic interfaces.

Additional Layers and other Extended Three-Dimensional Structures

Further, the microfluidic transport system need not be confined to twolayers (i.e., a first planar arrangement for transporting microdropletsof fluidic material in two spatial dimensions and second planararrangement for transporting microdroplets of fluidic material in twospatial dimensions) as described in the examples provided thus far. Forexample, at least a third planar arrangement for transportingmicrodroplets of fluidic material in two spatial dimensions can beconnected by at least one conduit situated between the first planararrangement and third planar arrangement, the at least one conduitconnecting the first planar arrangement and third planar arrangement andarranged to permit at least one microdroplet of fluidic material to movebetween the first planar arrangement and third planar arrangement. Forexample, the system can be arranged so that a microdroplet of fluidicmaterial is transported by the first planar arrangement, then movedthrough the at least one conduit, and then transported by the thirdplanar arrangement.

As an example, FIG. 40a depicts three planar arrangements fortransporting microdroplets of fluidic material in two spatial dimensions(heavier-lined) arranged with openings for interlinking conduits and aconnecting section (lighter-lined) providing conduit pathways betweenthese two layers. The conduit pathways can be passive passage ways orcan comprise electrodes or other transport mechanisms. It is understoodthat in some embodiments the connecting section can be omitted and theplanar arrangements can be directly connected. For the case where theconnecting section is employed, FIG. 40b depicts a final assembly of thethree example planar microdroplet transport arrangement layers assembledtogether interleaved with the two example connecting sections presentedin FIG. 40a . Again, it is to be understood that in some embodiments theconnecting section can be omitted and the planar arrangements can bedirectly connected.

In such a way, a multiple-level three-dimensional droplet transportarrangement can be implemented, wherein each layer comprises for examplea planar arrangement for transporting microdroplets of fluidic materialin two spatial dimensions, and the layers are joined by one or moreconduits in the manner described extensively above for the two-layercase. FIG. 40c depicts a representation of an example comprising somenumber of planar microdroplet transport arrangement layers, said numbergreater than three. Again, it is to be understood that in someembodiments the connecting section can be omitted and the planararrangements can be directly connected.

In one approach, pairs of planar microdroplet transport arrangementlayers are connected strictly pairwise, for example as suggested in FIG.41a . Alternatively, various embodiments and implementations canadvantageously configure, for example, the at least one connectingconduit to be an extension of a conduit used to link a given planarmicrodroplet transport arrangement layer with another planarmicrodroplet transport arrangement layers. FIG. 41b depicts an examplewherein at least one common extended conduit is used to connect threemicrodroplet transport arrangement layers. These approaches can becombined, for example as depicted in FIG. 41 c. In these, again it is tobe understood that in some embodiments the connecting section can beomitted and the planar arrangements can be directly connected.

Using such approaches, a connective topology among three or moremicrodroplet transport arrangement layers can be implemented. Forexample, FIG. 42a depicts an arrangement that implements a connectivedroplet transport topology of at least the linear three-dimension(‘cube’) lattice depicted in FIG. 42b . As each microdroplet transportarrangement layer can have a rich two-dimensional internal transportcapability, the arrangement depicted in FIG. 42a can implementconnections among other types of planar lattices. In these, again it isto be understood that in some embodiments the connecting section can beomitted and the planar arrangements can be directly connected.

Further, by incorporating some conduits between adjacent layers andother conduits that pass through adjacent layers in a sealed manner orotherwise bypass fluidic access, connective topologies among the layerscan be implemented other than a linear three-dimension (‘cube’) lattice.For example, a topological ring, torus, hyper-torus, hypercube, andother inter-connective topologies can be realized as advantageous in animplementation or embodiment. As a simple example, FIG. 42c illustratesa group of pairwise conduits that interconnect the microdroplettransport lattices within the three depicted microdroplet transportarrangement layers in a ring topology. In these, again it is to beunderstood that in some embodiments the connecting section can beomitted and the planar arrangements can be directly connected.

Non-Planar Layers

It is to be understood that various embodiments and implementations canadvantageously incorporate non-planar layers in place of one or more ofthe aforementioned planar layers. For example, a curved layer in theshape of a sphere, hemisphere, ellipsoidal surface, or other arrangementcan be used as advantageous in an implementation or embodiment.

Topologically One-Dimensional Layers

It is to be understood that various embodiments and implementations canadvantageously incorporate topologically one-dimensional layers in placeof one or more of the aforementioned planar layers. For example, atopologically one-dimensional layer in the shape of a linear path,curved path, spiral path, helix, coil, or other arrangement can be usedas advantageous in an implementation or embodiment.

Implementation of a Microfluidic Bus

U.S. Pat. No. 8,032,258 and pending U.S. patent application Ser. Nos.13/251,286 and 13/251,288 teach conduit-based valve-controlledmultichannel microfluidic bus technologies for the transport ofcontinuous liquid, gas, and multiphase flows as well as burst transport.

Alternatively or in addition to this, various embodiments andimplementations can advantageously be organized as a microfluidic bus,using one or more levels of a three-dimensional microdroplet arrangementas a shared transport bus linking microfluidic subsystems implemented inone or more other levels of the three-dimensional microdropletarrangement. FIG. 43 depicts an example use of a single microdroplettransport arrangement layer configured to serve as a microfluidic bus inservice to four other microdroplet transport arrangement layers. Inthese, again it is to be understood that in some embodiments theconnecting section can be omitted and the planar arrangements can bedirectly connected.

Example Fabrication

The arrangements and embodiments as described above can be fabricatedwithin a printed circuit board, integrated circuit housing, or usingmaterials such as metal, glass, polymer, plastic, layered materials,fibrous materials, etc. Manufacturing techniques can employ multi-stageassembly and/or functional printing (popularly known as “3D printing”).

Adaptations to Chemical, Biochemical, and Other Microfluidic Systems

The arrangements and embodiments as described above can be used for awide range of applications including microfluidic systems, chemicalreactors, biochemical reactors, chemical analysis arrangements,biochemical analysis arrangements, and other apparatus.

For example, a each layer in the three-dimensional microdropletarrangement can fluidically interface to one or more chemical and/orbiochemical reactor elements, one or more chemical and/or biochemicalanalysis arrangements, one or more cell culture chambers, one or morechemical and/or biochemical sensors, one or more controlled valves,and/or other apparatus within that layer, for example as suggested inFIG. 44a . The resulting layer can be combined with other layers, forexample as depicted in FIG. 44 b.

Other more specialized arrangements can also be provided. For example,the detailed arrangements provided earlier and variations upon them canbe modified so that membrane elements are used in place of the manydepicted thermal interface elements,

Additionally, the heat transport capabilities described can be used toprovide highly localized cooling, heating, temperature regulation, andthermal equilibrium operations to chemical and/or biochemical reactorelements, one or more chemical and/or biochemical analysis arrangements,one or more cell culture chambers, one or more chemical and/orbiochemical sensors, etc.

Example Applications

The arrangements and embodiments as described above can be used for awide range of applications relating to heat transfer, fluidic transfer,and other uses, and can be implemented within a printed circuit board,integrated circuit housing, or using materials such as metal, glass,polymer, plastic, layered materials, fibrous materials, etc. Exampleapplications include integrated circuit cooling, energy harvesting,microfluidic systems, chemical reactors, biochemical reactors, chemicalanalysis arrangements, biochemical analysis arrangements, and otherapparatus.

For example, the arrangements and embodiments as described above can beapplied to a wide range of electronic cooling and energy harvesting forheat-producing integrated circuits and other electronic components incomputers, particularly in large high-density blade servers and datacenter environments, as taught in pending U.S. patent application Ser.No. 13/385,411.

As another example, the arrangements and embodiments as described abovecan be applied to microfluidic chemical processing systems. In suchsystems it is difficult to localize significant variations intemperature. Some micro-reactor chemical reactions require heat whileother micro-reactor chemical reactions give off heat. Variousembodiments and implementations can thus be useful in creating localizedtemperature environments, removing heat of reactions, and harvestingpower from heat of reactions.

As yet another example, the arrangements and embodiments as describedabove can be applied to microfluidic biochemical processing systems. Insuch systems it is important to localize and precisely controltemperature. Some micro-reactor biochemical reactions require heat whileother micro-reactor biochemical reactions require heat to be removed.Various embodiments and implementations can thus be useful in creatinglocalized temperature environments, removing heat from reactions, and insome cases even provide harvesting of power from the heat of biochemicalreactions.

As a further example, the arrangements and embodiments as describedabove can be applied to microfluidic bioreactor systems. In such systemsit is difficult to localize significant variations in temperature. Insuch systems it is important to localize and precisely controltemperature. Some bioreactor processes require heat while otherbioreactor processes require heat to be removed. Various embodiments andimplementations can thus be useful in creating localized temperatureenvironments, removing heat from reactions, and in some cases evenprovide harvesting of power from the heat of bioreactor processes.

CLOSING

The terms “certain embodiments,” “an embodiment,” “embodiment,”“embodiments,” “the embodiment,” “the embodiments,” “one or moreembodiments,” “some embodiments,” and “one embodiment” mean one or more(but not all) embodiments unless expressly specified otherwise. Theterms “including,” “comprising,” “having” and variations thereof mean“including but not limited to,” unless expressly specified otherwise.The enumerated listing of items does not imply that any or all of theitems are mutually exclusive, unless expressly specified otherwise. Theterms “a,” “an” and “the” mean “one or more,” unless expressly specifiedotherwise.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the implementation to the precise forms disclosed. Manymodifications and variations are possible in view of the aboveteachings. The embodiments were chosen and described in order to bestexplain the principles of the implementation and its practicalapplications, to thereby enable others skilled in the art to bestutilize the implementation and various embodiments with variousmodifications as are suited to the particular use contemplated.

While the implementation has been described in detail with reference todisclosed embodiments, various modifications within the scope of theinventive concept will be apparent to those of ordinary skill in thistechnological field. It is to be appreciated that features describedwith respect to one embodiment typically can be applied to otherembodiments.

The inventive concept can be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the inventive conceptbeing indicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

Although exemplary embodiments have been provided in detail, variouschanges, substitutions and alternations could be made thereto withoutdeparting from spirit and scope of the disclosed subject matter asdefined by the appended claims. Variations described for the embodimentsmay be realized in any combination desirable for each particularapplication. Thus particular limitations and embodiment enhancementsdescribed herein, which may have particular advantages to a particularapplication, need not be used for all applications. Also, not alllimitations need be implemented in methods, systems, and apparatusesincluding one or more concepts described with relation to the providedembodiments. Therefore, the implementation properly is to be construedwith reference to the claims.

The invention claimed is:
 1. A microfluidic transport system fortransporting microdroplets of fluidic material in three spatialdimensions, the system comprising: a first planar arrangement fortransporting microdroplets of fluidic material in two spatialdimensions, the first planar arrangement comprising a first array ofelectrodes, the first array of electrodes configured for controlledtransport of microdroplets responsive to electric fields created byelectrical operation of at least some of the electrodes within the firstarray of electrodes; a second planar arrangement for transportingmicrodroplets of fluidic material in two spatial dimensions, the secondplanar arrangement comprising a second array of electrodes, the secondarray of electrodes configured for controlled transport of microdropletsresponsive to electric fields created by electrical operation of atleast some of the electrodes within the second array of electrodes, anda first conduit situated between the first planar arrangement and secondplanar arrangement, the first conduit connecting the first planararrangement and second planar arrangement and arranged to form at leastone 3D micro-droplet transit structure to permit at least onemicrodroplet of fluidic material to move between the first planararrangement and second planar arrangement; wherein at least one of thefirst and second planar arrangements further comprise an interface to athermoelectric material, wherein the system is arranged so that amicrodroplet of fluidic material is transported by the first planararrangement, then moved through the first conduit, and then transportedby the second planar arrangement, wherein said transport is responsiveto electric fields created by at least electrical operation of at leastsome of the electrodes within the first array of electrodes and secondarray of electrodes.
 2. The microfluidic transport system of claim 1,wherein the first conduit further comprises at least one conduitelectrode.
 3. The microfluidic transport system of claim 2, wherein themicrodroplet moves between the first planar arrangement and secondplanar arrangement responsive in at least part to electrical operationof the conduit electrode.
 4. The microfluidic transport system of claim1, further comprising: a second conduit situated between the firstplanar arrangement and second planar arrangement, the second conduitconnecting the first planar arrangement and second planar arrangementand arranged to permit at least one microdroplet of fluidic material tomove between the first planar arrangement and second planar arrangement;wherein the system is arranged so that a microdroplet of fluidicmaterial is transported by the second planar arrangement, then movedthrough the second conduit, and then transported by the first planararrangement.
 5. The microfluidic transport system of claim 4, whereinthe second conduit further comprises at least one conduit electrode. 6.The microfluidic transport system of claim 1, further comprising: atleast a third planar arrangement for transporting microdroplets offluidic material in two spatial dimensions, the third planar arrangementcomprising a third array of electrodes, the third array of electrodesconfigured for controlled transport of microdroplets responsive toelectric fields created by electrical operation of at least some of theelectrodes within the third array of electrodes, and at least oneconduit situated between the first planar arrangement and third planararrangement, the at least one conduit connecting the first planararrangement and third planar arrangement and arranged to permit at leastone microdroplet of fluidic material to move between the first planararrangement and third planar arrangement; wherein the system is arrangedso that a microdroplet of fluidic material is transported by the firstplanar arrangement, then moved through the at least one conduit, andthen transported by the third planar arrangement, and wherein saidtransport is responsive to electric fields created by at leastelectrical operation of at least some of the electrodes within the firstarray of electrodes and third array of electrodes.
 7. The microfluidictransport system of claim 6, wherein the at least one conduit is anextension of the first conduit.
 8. The microfluidic transport system ofclaim 1, wherein the microdroplet comprises a thermofluid.
 9. Themicrofluidic transport system of claim 1, wherein the resulting systemprovides a heat transfer function by using the microdroplet to carryheat.
 10. The microfluidic transport system of claim 1, wherein thefirst planar arrangement further comprises an interface to a sensor. 11.The microfluidic transport system of claim 1, wherein the second planararrangement further comprises an interface to a sensor.
 12. Themicrofluidic transport system of claim 1, wherein the resulting systemprovides fluidic transport in a chemical reaction system.
 13. Themicrofluidic transport system of claim 1, wherein the resulting systemprovides fluidic transport in a chemical analysis system.
 14. Themicrofluidic transport system of claim 1, wherein the resulting systemprovides fluidic transport in a biochemical reaction system.
 15. Themicrofluidic transport system of claim 1, wherein the resulting systemprovides fluidic transport in a biochemical analysis system.
 16. Themicrofluidic transport system of claim 1, wherein the first planararrangement further comprises an interface to a membrane.
 17. Themicrofluidic transport system of claim 1, wherein the second planararrangement further comprises an interface to a membrane.
 18. Themicrofluidic transport system of claim 1, wherein the first planararrangement further comprises an interface to a reaction chamber. 19.The microfluidic transport system of claim 1, wherein the second planararrangement further comprises an interface to a reaction chamber.